Quartz sand acid leaching process and influencing factors

01Principle of quartz acid leaching

Quartz sand acid leaching utilizes the property of quartz sand insoluble in acid (except HF). The acid solution can dissolve other impurity minerals, remove iron, aluminum, calcium, magnesium and other impurities on the surface to achieve the purpose of purification. quartz.

02 Quartz acid leaching process

Quartz sand acid leaching commonly used hydrochloric acid, sulfuric acid, oxalic acid, hydrofluoric acid. The general process is crushing - water washing - magnetic separation - acid leaching - water washing - dehydration - drying. After the quartz sand is crushed, some impurities can be removed by washing with water, and more than 99% of the mechanical iron can be removed by magnetic separation. The following is the specific operation process of the acid leaching stage:

A certain concentration of hydrochloric acid solution is heated to a certain temperature and treated for 2-3 hours. The amount of hydrochloric acid is about 5% by weight of the quartz sand.

After washing, the quartz sand is mixed with concentrated hydrochloric acid and sulfuric acid (98%) and left at room temperature for 1-2 hours. Or stir the mixed solution with quartz sand for a period of time to wash away the acid.

Mix water, oxalic acid and copper salt in a certain proportion at a certain temperature to form a solution. The quartz sand and the solution are mixed and stirred in a certain proportion. After a few minutes, the solution was filtered off and recycled after treatment. The quartz sand is washed, dehydrated and dried.

Add hydrofluoric acid for treatment. Hydrofluoric acid works better alone, but requires higher concentrations. Lower concentrations of hydrofluoric acid can be used with sodium metabisulfite.

A certain concentration of hydrochloric acid and fluosilicic acid solution are added to the quartz mortar liquid at the same time. It can also be treated with hydrochloric acid solution first, washed with water and then treated with fluosilicic acid. Or reverse the order, heat for 2-3 hours, then filter and wash.

03 Influencing factors of quartz acid leaching

 (1) Acidity

The acid leaching process is actually a chemical reaction between impurities and acid. Under certain conditions, the concentration and composition of various acids are different, and the effects of reacting with impurities are also different. Practice shows that at a certain temperature, if the acidity is appropriately increased, the more reactant molecules per unit volume, the more activated molecules. Practice has shown that at a certain temperature, if the acidity is appropriately increased, the more reactant molecules per unit volume and the more activated molecules, the reaction speed will be accelerated and the acid leaching effect will be improved.

(2) Temperature

Temperature is the decisive factor for the acid leaching effect of quartz sand. Associated minerals of quartz sand, such as epidote and rutile, can react with acids at room temperature. If heated during acid leaching, the effect increases with increasing temperature. The difference in the treatment effect between winter and summer is mainly due to the difference in outside temperature.

(3) Time

Under the condition of constant temperature and constant acid, the length of quartz acid leaching time directly affects the impurity removal effect. In winter, the outside temperature is low, and the mineral impurities in quartz react slowly with acidic substances, and it takes a certain period of time to achieve the desired effect.

In addition, the acid leaching time is also related to the particle size of the quartz sand. When the quartz particles are small, the contact area with the acid is large, and the reaction speed is fast. The opposite is true if the quartz particles are large. At this time, the reaction time should be extended to achieve the desired acid leaching effect.